The invention relates to a device for transporting and temporarily storing a web-like recording medium in an electrographic printer or copier.
Such a device is taught in DE 41 077 99 C2, for example. The recording medium of paper is transported there by friction from an input station into the interior of the device via a roller system with a driven roller. A driving mechanism is provided there with which the recording medium is transported to a transfer printing station.
In the known arrangement, a decoupling of the drive mechanism at the input side from the drive mechanism of the recording medium in the printer is further provided. Fluctuations arising at the input drive mechanism or at the internal printing drive mechanism are thus picked up to a certain extent. Such a decoupling is necessary, particularly when another device is connected to a printer upstream, for example, of a first printer which prints the reverse side of an continuous paper web and feeds this paper web to the second printer, which prints the reverse side. A paper changing station is then introduced in the paper web between these two printers.
In printing situations wherein large speed differences occur within a short time, the known arrangement has the disadvantage that the jolt buffer only cushions hard jolts which would result in a tearing of the paper. Jolts which do not activate the jolt buffer exert a full effect on the paper web. A not inconsiderable portion of impact forces act therewith not only on the paper web, but also on the remaining components which drive the paper web.
The disadvantage just described adversely affects the printing quality if the impact forces are manifest up into the region of the transfer printing station. There they effect displacements of the printing image. Such displacements are not acceptable. This effect can arise, on the one hand, in extreme start or stop situations in which high acceleration forces act on the paper web, and on the other hand, when a prescribed paper transport unit is to be utilized in a printer, this printer producing a new, higher resolution in the region of the transfer printing station. The thinner and thus lighter the respectively utilized paper is, the more negative is the effect which the jolts created by a given paper transport have on the printing quality.